VS 2008 generates a x64 Perl without any issues for me. VS 2003 also generates a 32 bit Perl without any issues for me. You know that VC 10 is also a synonym for Visual C++ 4.0 ? ;-)

edit: if you didn't understand the jk, _MSC_VER == 1000 is Visual C 4. So VC 4's official name is "Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 10.00.5270 for 80x86" which abbreviates to "MS C V10" or "MS C 10", which is fudged to "VC 10". Realistically, in 2012, you can bet VC 10 means VC 2010.

Also AS uses a Platform SDK for x64 that was released between 2003 and 2005. This is because until VS 2005 was released x64 Platform SDK linked with x64 msvcrt.dll not a VS version specific CRT. The C compiler included in the DDK, if used to compile usermode code, will still compile with msvcrt.dll and not a VS specific DLL. AS has a policy for AP to only use msvcrt.dll. Google for more info.